Expulsion fuse



July 19, 1932. C, H, THOMAS l,67,899

EXPULS ION FUSE Filed Nov. 17, 1930 Patented July 19, 1932 1,7 i

UNITED STATES PATENT OFFICE i CYRIL H. THOMAS, F FLOSSMOOR, ILLINOIS EXPULSION FUSE Application led November 17, 1930. Serial No. 496,081.

My invention relates in general to electric has blown no portion capable of forming high fuses andhas more particular reference to a resistance leaks remains in series between the fuse of the expulsion type in which a Vfusible' spaced fuse clips. element, adapted to melt under predetermined Still another important object is to prooverload conditions in the fuse current, is car` vide a fuse holder of the class described ried in a housing from which it may be eX- which is mountable as a unit in a standard pelled forcibly when the fusible element melts high voltage fuse mounting. whereby to quickly attenuate and extinguish Among the other important objects of the the arc formed by the fusion of the link and invention is to provide a cheap, simple, ruglf' hence to interrupt the current. p' ged fus-e holder, positive in operation, ca- 60 It is an important obj ect of my present inpablo of assembly in standard fuse clips withvention to provide an electric fuse which is out the use of special adapters or other eX- reliable and positive in operation and capable traneous devices and having numerous other of acting promptly to protect an overloaded features of advantage, which will become apelectrical circuit by quickly and completely parent as the invention is more fully under? 65 extinguishing the electric arc formed by the stood from the following description which, melting of the fusible element. l taken in connection with the accompanying Another important object is to provide a drawing discloses a preferred embodimentk lfuse formed to utilize the force of the are of my invention.

itself most effectively to eXpell or project the Referring to the drawing:

. arc and the remaining portions of the fusible Figure 1 is a perspective view, partially element in such a, manner as t0 insure the, atin Section t0 reveal details Of COIlStlllCtiOIl, of tenuation and extinction of the arc and the a fuse and fuse hOldeI embodying my present consequent rupture of the circuit in which invention; and

the fuse is arranged to protect'the circuit Figure 2 is a vertical cross section taken from overloads, the device of my present insubstantially along the line 2-2 in Figure 1. vention being so constructed that when the To illustrate my invention I have shownI on fusible element is melted as by an overload,` the drawing a fuse holder demountably aruit is expelled in a direction and in a manner ranged in operative position between the c oquickly to extinguish the arc formed at the operating blades of the lspaced apart clips point of fusion of the fusible element. v or fuse holder mountings 11 of a standard It is a further object of the invention to fuse mounting or support. provide a Vfuse holder or support of simple, The fuse holder consists of a fuse support rugtfged and economic form, which can be comprising a pair of spaced ferrules or caps manufactured cheaply, which can be readily 15 supported in spaced relation at the op-V dis-connected from the line for replacement posite ends of a suitable insulating member of the fusible'element, and which is inter- 13, which may be formed as a tube of relachangeable in the spaced mounting elements tively heavy insulating material, preferablyV Aor clips of standard fuse support mountings glass, the caps l5 being provided with sockat present in general use. ets 21 into which the ends of the member 13 Another important object of my invention are secured as by means of bushings'19 orI is to fprovide a fuse holder Vor support of the other suitable packing. The caps lare prefexpulsion type, all parts of which are, when erably cylindrical and provided with a lonn the holder is mounted in its spaced supportgitudinal bore 23 opening into the bottom of 4" ing clips or mountings at all times, firmly the sockets 21 for the purpose of lightening supported from at least two spaced apart the support and conserving the material from points to insure that the support is firmly which the parts 15 are made. The tube13 mounted againstl displacement by the eX?. and ferrulesl of course may be made solid, plosive forces liberated-when the fuse operif desired. The ferrules are` adapted to enm ates or blows and wherein after the fuse gage betweenvthe co-operating blades of la standard fuse mounting, the sides of the caps being formed as at 25 to provide bearing surfaces onopposite sides thereof, whereby the blades of the fuse clips may readily engage and grip the caps whereby to firmly support the fuse holder in position. The member 13 thus acts as a spacing means to insulate and space the ferrules 15 apart.

The support comprising the member 13 and the ferrules 15, also, when assembled between the spaced clips or mounting elements 11 forms a firm base on which the expulsion devices may be securely mounted. In my present invention the fusible element is not mounted to extend between the ferrules within the member 13 as in expulsion fuses previously provided, an example of which is illustrated and described in my co-pending application, Serial No. 333,315, filed January 18, 1929. In order to avoid the necessity. of

providing a fibre or other suitable fire resistant liner extending between the ferrules within the member 13 to protect it and the ferrules 15 from destruction due to the intense heat of the arc, as has been the Ypractice heretofore, the objection to the provision of a liner being that it absorbs moisture to a certain extent and forms a high resistance electrical leak between'the ferrules so that even after the fuse is blown, the circuit is still closed through the high resistance leak pro-V vided by the charred liner. In my Apresent fuse support, I provide means for supporting the fusible link between the ferrulos outside of the support and eliminate the liner between the ferrules to thus overcome the disadvantages aforesaid. This construction permits me topprovide an expulsion means comprising an explosion chamber supported by one ferrule and having an outlet point downwardly away from the support member so as to direct the arc substantially away from the other ferrule which is never subjected to the damaging effects of the arc and hence the lire resistance lining heretofore employed may be entirely dispensed rwith or at most diminished in length to terminate far` short of the remote ferrule to provide a rudimentary barrel extending from the explosion chamber solely for the purpose of givingdirection to the expulsion of the arc and not necessarily to protect the ferrules or the spacing insulating tube 13. By thus eliminating the elongated liner, I reduce expense since the liners used in the devices heretofore provided have ever been a source of trouble and expense as pointed out in my co-pending application aforesaid.

In the device of my present invention, means is providedA for electrically connecting the opposed ends of a fuse link 69 to the spaced lcaps 15, the fuse wire, however, extending between `the caps outside of the member 13 so that when the fuse operates,

I. the expulsion will-notpassout through the To accomplish the foregoing result, one i ferrule or cap 15 is provided with an expulsion device'comprising an off-set portion 27,7which may be conveniently formed integralwith the ferrule. The off-set portion comprises a cylindrical member provided with a longitudinal bore, the axis of which forms an angle with the longitudinal axis of the spacing member 13 and the caps 15. The bore provides a substantially wide open mouth 31 at the lower end of the portion 27. The mouth is threaded internally to asubstantial depth in order to.l threadingly receive the threaded end of a tubular member 43, which is or may be formed of bakelite, horn fibre, porcelain or other suitable heat resisting material. The. bore of the cylindrical portion 27 extendsv inwardly of the threaded portion, being preferably restricted sufficiently to form a continuation of the bore of the tube 43 andy toprovide an explosion chamber 37. The bore of the portion-27 is restricted behind the explosion chamber 37 and opens onto the upper end of the off-set portion as a relatively small opening 39 sufliciently large to permit the fuse link to be inserted therethrough.

VThe other ferrule 15 is provided with an y outwardly extending boss 29 havinga cen-` tral threaded stud 3 1, extending outwardly thereof and carryingV a thumb nut 33, whereby one end of the fuse wire 69 may be electrically connected, to the ferrule.

The upper end of the. cylindrical portion 27 is preferably restricted and is. externally threaded at 35 to receive a Ycap 51 provided to seal the opening 39 into the explosion chamber 37 and to secure the upper end of the fuse wire to the portion 27.

The fuse 69 preferably consists. of a wire which may be formed of any well known or suitable fusible material such for instance yas'aluminunnzinc or copper, either pure or alloyed, with other materials. Of' course othery or special fuse links may be employed. Thel wire at itsupper end is formed to provide an outwardly extending stop 45, whereby when the fuse is introduced through the restricted opening 39 in the upper end of the portion 27, this outwardly extending stop will lie upon the top of the threaded portion 33 as shown in the drawing. TheA stop 45 maybe conveniently formed by curl` ing the end` of` the fusewire annularly in aY plane perpendicular to the remaining portions ofthe wire. They lower portions of l the fuse wire` from a pointspaccd below thel upper curled end thereof may be plaitcd or otherwise coiled with a second length of wire in order to insure that the initial fusion vol the link will occur in theupper portions, that is, substantially in the'explosion chamber 37 when the fuse is arranged 'in position in the fuse holder.

The fuse may be arranged in the fuse holder by removing the cap 41 and inserting the lower end of the fuse Wire through the opening 39 and passing the same downwardly through the explosion chamber 37 and tube 43 until the upper curled end of the fuse wire engages the top of the portion 33. The cap 51 may then be threaded upon the portion 33 to secure the upper end of the fuse wire firmly against the top of the housing 27, and in order to seal the opening 39 so that the force of the explosion caused by the burning of the fuse wire in thechamber37, will be directed downwardly through the tube 4:3 to thus expel the remaining unburned portions of the fuse link 69. The fuse link 69 is suiliciently long to extend out through the open end of the tubular member lf3 and the free plaited end of the fuse link 69 is finally secured to the remote ferrule by means of the thumb nut 33 so as to electrically connectthe spaced ferrules by means of the fuse link 69.

It will be noted that the tubular member 43 extends diagonally outwardly from the ferrule 15 at an angle with the axis of the elongated support comprising the member i 13 and the spaced caps 15, so that the force of the explosion is directed substantially away from the other cap 15. The portion 27, which contains the explosion chamber land which, therefore7 will be subjected to `considerable recoil reaction when the fuse blows, is firmly supported from the lfuse clips, not only because the ferrule on which it is mounted is rmly held between the arms of the clip, but also because it is mechanically connected to the remote ferrule and fuse clips, so that the force of the explosion and expulsion is carried in part by both clips. In other words, the explosion housing is supported in part by bothof the f lspaced fuse supporting clips to the end that the entire assembly is firmly secured in operative position, whereby to reduce the possibility of dislodgment of the explosion housing during the discharge of the fuse.

My present invention entails the arrangement of the are expelling devices in position to expell the arc in a direction which does not co-incide with the axis of the support member and so it is all the more necessary to preserve the strength and rigidity of the mounting.

It is thought that the other advantages of the explosion fuse of my invention, including the simplicity of construction and also the fact that the fuse assembly may be mounted in standard fuse supports, will be clearly( be madeJ in the form" construction and ar-v rangement of the several parts without departing from the spirit or scope of my present inventionor sacrificing any of its attendant advantages, the'form hereinbefore described being a preferred embodiment for the Vpurpose of illustrating my invention. i

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is: Y Y

1; A fuse support comprising an elongated support member, including two spaced apart members, insulating means between said members for maintaining their spaced relationship, said members being formed for connection to fuse support mounting elements, one of saidV membersbeing formed with an explosion chamber opening at an angle with 3. A fuse support comprising an elongated) member providing spaced insulated terminals to which a fuse may be attached, one of said terminals having an integral olf-set portion forming an explosion housing, opening in a direction other than directly toward the other terminal, and means to connect remote portions of a fusiblemember electrically to said spaced terminals with a portion of the fusible member extending in said explosion housing, whereby the explosion housing is supported at all times from both terminals and whereby after the link is fused, there is no electrical connection whatever between the terminals. i'

4. A fuse support comprising an elongated member having insulated and spaced apart ferrules at least one of which is adapted for detachable engagement in a fuse support mounting and an olf-setV explosion housing carried by one of the ferrules in position such that the opening of the explosion housing exa longitudinal bore internally threaded at the mouth thereof, a tube of fire resistant material threaded into said bore,

saidbore being extended behind the inner end of said tubular member to form an explosionfchamber vand 25- ship, said explosion housing being continued behind the explosion chamber as a restricted opening at the opposite end of the explosion housing, said opposite end of the housing being threaded to'receive a cap .5i for sealing thel restricted opening whereby a fuse link may be inserted through the restricted opening and clamped at one endkby and between the cap and the threaded end of the explosion housing to extend thence 101 through the explosion chamber and then through the tubular member, and means in said other ferrule being provided with means for making an electrical connection with a remote portion of the fuse link, said tubular :member being terminated short of said remote portion.

5. A fuse support comprising means forming an explosion housing and supporting means to support said housing from spaced apart fuse clips, said supporting means com- `minating short of said other ferrule, means to connect a fusible link to said other ferrule whereby the link may extend from said ferrule through the opening of said explosion housing through said explosion chamber and Imeans to connect a remote portion of said link to saidexplosion housing in the bottom thereof. y

6. A fuse support comprising an elongated member having spaced portions adapted for (connection to fuse support mounting eiements one of said portions having means forming andexplosion chamber opening at the side of the member in a direction pointing substan tially away from the other portion and means for connecting a fusible member between said portions to extend through said opening.

7. The combination with fuse clips of a fuse holder comprising an elongated member having spaced portions adapted for connection to fuse support mounting elements, one

of said portionshaving means forming an explosion chamber opening at the side of the member in a direction pointing substantially away from the othe1 portion, and a fusible I link mounted between said portions and hav ing a portion extending in said chamber and through said chamber opening, said fusible link having means to insure fusion at the portion extending in the chamber whereby the i arcset up will expell itself and the remainder of the link outwardly of the elongated member.

8; The combination with yfuse support mounting elements of a fuse holder compris- 5 ing an elongated member havingspaced portions adapted for connection to fuse support mounting elements, one of said portions having means .forming an explosion chamber opening at the side of the member in a'direction pointing substantially away from the other portion and a fusible link having spaced portions detachably connected to said spaced portions and extending through said chamber and out through said opening.

9. An electric fuse comprising an elongated member o f insulating material, metallic members formed to fit fuse support mounting elements secured to the ends of the elongated member, one of said metallic members being formed with a housing opening at the side of the member and a fuse element connected to the lsaid member and extending in said housing and out through the opening thereof` said element extending outside of said elongated member to the other metallic member.

l0. An electric fuse comprising an elon gated member of insulating material, metallic members formed to lit fuse support mounting elements secured to the ends of the elongated member, one of said metallic members being formed with a housing opening at the side of the member and a fuse element detachably connected to the said member and extending in said housing and out through the opening thereof, said element extending outside of said elongated member to the other metallic member an d means to detachably connect the fuse element to said other member.

ln witness whereof, I have hereunto sub scribed my name.

CYRIL H. THOMAS. 

